|
US2514578A
|
Sound recording and reproduction system |
Expired / Lapsed
|
1948-03-25 |
1950-07-11 |
0 |
Details
|
|
US2321812A
|
Tape driving system for magnetic sound recording machines a… |
Expired / Lapsed
|
1940-11-19 |
1943-06-15 |
0 |
Details
|
|
US2213631A
|
Method of and apparatus for magnetically recording sound |
Expired / Lapsed
|
1937-10-25 |
1940-09-03 |
0 |
Details
|